Zinc mediated activation of terminal alkynes: stereoselective synthesis of alkynyl glycosides

Tatina, Madhu Babu; Kusunuru, Anil Kumar; Yousuf, Syed Khalid; Mukherjee, Debaraj

doi:10.1039/c4ob01405g

Cited by 26 publications

(15 citation statements)

References 30 publications

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“…[103,104] Although HCl in Et 2 O is the most popular acid for activation of acetals in the NaBH 3 CN-mediated ring opening, other electrophiles have been explored as well, such as methanesulfonic acid, [105] triflic acid, [106] molecular iodine [107] and cyanuric chloride. [108] About at the same time the NaBH 3 CN method was disclosed, experiments using borane complexes, such as borane-trimethylamine (BH 3 ·NMe 3 ), borane-dimethylsulfide (BH 3 ·SMe 2 ) and borane-tetrahydrofuran (BH 3 ·THF), were being published. The first reductive opening in pyranose systems with BH 3 ·NMe 3 was reported in 1983 by Garegg and co-workers.…”

Section: Reductive Methodsmentioning

confidence: 99%

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Regioselective Ring Opening of 1,3‐Dioxane‐Type Acetals in Carbohydrates

et al. 2018

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The (regio)selective manipulation of hydroxyl groups in carbohydrates has been a long‐standing challenge in (bio)organic chemistry and continues to trigger the creative minds of many chemists. Among the various strategies that have been developed to address these issues, mostly relying on multistep procedures involving the use of protecting groups, the regioselective ring opening of 1,3‐dioxane‐type acetals has emerged as a powerful tool. Since the first papers on this subject appeared in the 1960s, a large variety in both acetal types and reagents for their partial cleavage has come to the fore. This review aims to give an overview of the different carbohydrate‐derived ring systems, ranging from four‐ to seven‐membered rings, on which regioselective ring‐openings have been performed, along with the appropriate reagents and combinations thereof. The transformations on 1,3‐dioxane acetals fit in a larger group of ring opening reactions of structurally related cyclic functional groups, including 1,3‐dioxolanes, 1,3‐oxathianes, orthoesters, cyclic carbonates and silylene acetals, which will not be discussed in this review.

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Section: Reductive Methodsmentioning

confidence: 99%

“…Although HCl in Et 2 O is the most popular acid for activation of acetals in the NaBH 3 CN‐mediated ring opening, other electrophiles have been explored as well, such as methanesulfonic acid, triflic acid, molecular iodine and cyanuric chloride …”

Section: Pyransmentioning

confidence: 99%

Regioselective Ring Opening of 1,3‐Dioxane‐Type Acetals in Carbohydrates

et al. 2018

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“…This reagent is a stable, nonvolatile, and inexpensive substrate that highlighted it in organic synthesis as an applicable reagent. Synthesis of benzopyran , synthesis of thiiranes , functionalization of glycosides , synthesis of 2‐substituted benzofurans , oxidation of alcohols , synthesis of sulfonamides , Beckmann rearrangement , synthesis of quinazolinones , synthesis of homoallylic alcohols , Friedel–Crafts acylations , synthesis of indole derivatives , synthesis of α‐amino nitriles , and preparation of hydroxamic acids are only part of the applications of this valuable reagent in organic synthesis.…”

Section: Introductionmentioning

confidence: 99%

Selective and Efficient Formylation of Indoles (C3) and Pyrroles (C2) Using 2,4,6‐Trichloro‐1,3,5‐Triazine/Dimethylformamide (TCT/DMF) Mixed Reagent

Iranpoor

Panahi

Erfan

et al. 2016

Journal of Heterocyclic Chem

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This study introduces an efficient method for the selective formylation of indoles and pyrroles at the positions of C(3) and C(2), respectively. The mixture of three equivalents of N,N‐dimethylformamide and one equivalent of 2,4,6‐trichloro‐1,3,5‐triazine (cyanuric chloride) generates an easy handling formylating agent for the efficient formylation of these classes of compounds to give the corresponding aldehydes under mild reaction conditions. This procedure was highly efficient, and a range of formylated indoles and pyrroles were obtained in good to excellent yields.

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“…Despite having no success using this methodology in the alkynylation of 2-haloglycals 57, the alkynylation of 2-formylglycal 66 was attempted using Mukherjee's conditions. [26] Bromomethyl acetate (1 eq) and trimethylsilylacetrylene (1.5 eq) was added to a solution of zinc powder (1.5 eq) in 1,2-dichloroethane (Scheme 3.18). After stirring at 40 °C for 1 h, 2formylglycal 66 (1 eq) was added.…”

Section: Exploration Of Mukherjee's Methodology For Ferrier-type Alkynylation Of 66mentioning

confidence: 99%

“…Scheme 2.9: Alkynylation of acetate protected 2-acetoxyglycals reported by Murkerjee. [26] Ferrier-type C-glycosidation of 2-formylglycals (70, Scheme 2.10) with aliphatic nucleophiles has been reported by Cossy. [27] Like the above reaction reported by Murkerjee, Cossy's method utilises an in situ generated organometallic species.…”

Section: Acetylene Nucleophiles Have Been Installed Via Ferrier-type Alkynylation As Demonstrated Bymentioning

confidence: 99%

Toward the Synthesis of the Fungal Metabolite (-)-TAN-2483B

Phipps¹

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<p>In the search of chemical species with potential therapeutic biological activity, synthetic chemists have looked to nature for inspiration. Molecules built by biological machinery often have structures predisposed for biological interaction. (-)-TAN-2483B and the related compounds (-)-TAN-2483A, and waol A are fungal metabolites that display biological activity in kinase inhibition and parathyroid-induced bone resorption. Though total syntheses of (-)-TAN-2483A and waol A have been achieved, the established methodology does not afford access to (-)-TAN-2483B owing to the unique relative configuration about the ring system. Derivatives of D-galactal have been synthesised, and functionalised at the C-1 and C-2 positions, laying the groundwork for a route to (-)-TAN-2483B and analogues. Using D-galactal derivatives is advantageous as it circumvents some difficult transformations in the existing method for analogue synthesis. The functionalities installed were halide and formyl groups at the C-2 position, and acetylenes at the C-1 position. The synthesis of 2-haloglycals from tri-O-acetyl-D-galactal using N-halosuccinimides was achieved in 32% and <37% for the bromo- and iodo- variants respectively. Vilsmeier-Haack formylation was explored using per-benzylated and per-acetylated galactals as substrates. Formylation of the per-benzylated species was achieved in 78% yield in accordance with literature values. Vilsmeier-Haack formylation on the per-acetylated galactal has not been reported and the glycal was found to be a poor substrate for the formylation. Theories regarding the incompatibility of the per-acetylated species with Vilsmeier-Haack conditions were developed. Ferrier-type alkynylation of the 2-halo/formylglycals was explored, with yields up to 17% and 13% for the bromo- and iodo- species (unoptimised), and 7% for 2-formylglycal (after optimisation studies). The resulting 1-ethynyl-2-formyl/halo-2,3-unsaturated pyrans could be potential intermediates en route to the furanone ring of the target compound.</p>

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Zinc mediated activation of terminal alkynes: stereoselective synthesis of alkynyl glycosides

Cited by 26 publications

References 30 publications

Regioselective Ring Opening of 1,3‐Dioxane‐Type Acetals in Carbohydrates

Regioselective Ring Opening of 1,3‐Dioxane‐Type Acetals in Carbohydrates

Selective and Efficient Formylation of Indoles (C3) and Pyrroles (C2) Using 2,4,6‐Trichloro‐1,3,5‐Triazine/Dimethylformamide (TCT/DMF) Mixed Reagent

Toward the Synthesis of the Fungal Metabolite (-)-TAN-2483B

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